Since polypropylene series resins are excellent, for example, in heat resistance, chemical resistance and steam barrier property, as well as blow molded products (hollow molded containers) thereof are also excellent in the rigidity and impact shock resistance, they are generally used for tableware containers, detergent containers, medical containers for fluid supplementation. However, the blow molded containers made of polypropylene having such excellent properties have a problem in that the transparency is insufficient. In particular, high transparency is required in the medical containers for fluid supplementation so that obstacles in the liquid contents can be observed.
Heretofore, as a method of improving the transparency of polypropylene molded products, there has been proposed, for example, to apply heat molding with addition of a nucleating agent such as dibenzilidene sorbitol or di(alkylbenzilidene)sorbitol (refer to Japanese Unexamined Patent Publication Nos. 22740/1976, 117044/1978, 30449/1981 and 225143/1983).
However, when the polypropylene resin is molded under heating being blended with dibenzilidene sorbitol or di(alkylbenzilidene)sorbitol, odors are caused during heat molding and the resultant molding products have odors. In a case of using them as containers for fluid supplementation, there is also a safety and sanitary problem such as leaching of the nucleating agent to the fluid supplementation.
For overcoming such a problem, there has been proposed a method of adding a high molecular compound such as 3-methylbutene-1 polymer or vinyl cycloalkane polymer as a nucleating agent (refer to Japanese Examined Patent Publication No. 32430/1970 and Japanese Unexamined Patent Publication No.139731/1985) but higher transparency has been demanded.